Comparative study of the phenotype and virulence of recent serovar 1a, 1b, and 2a isolates of Erysipelothrix rhusiopathiae in Japan.

Erysipelothrix rhusiopathiae causes swine erysipelas (SE) and is classified -into 16 serovars based on cell surface antigens. Our previous study suggested that recent SE outbreaks were mostly caused by serovar 1a of E. rhusiopathiae with the surface protective antigen (Spa)A protein characterized by methionine and isoleucine at positions 203 and 257 (M203/I257 SpaA). In this study, four recent E. rhusiopathiae isolates comprising two serovar 1a with M203/I257 SpaA strains (2012 Miyazaki and 2012 Chiba), one serovar 1b strain (2015 Miyazaki), and one serovar 2a strain (2012 Nagano) were compared with each other and with the serovar 1a Fujisawa reference strain regarding in vitro phenotypes and in vivo virulence in mice and pigs. The serovar 1b and 2a strains, which are the less prevalent strains in the field in Japan, showed lower growth in liquid culture and lower virulence in animals than the serovar 1a variants. Adhesion of the serovar 2a strain to porcine endothelial cells was weaker than that of the serovar 1a and 1b strains. Several advantages of serovar 1a strains were found, but no plausible cause of the M203/I257 SpaA type variants to be selected for the most prevalent strains among serovar 1a strains was identified in this study.

Potential risk factors of swine erysipelas outbreak in Northeast Mainland China.

Swine erysipelas is a common infectious disease that affects the pig-breeding industry. The purpose of this study was to elucidate the risk factors and their role in the prevalence of swine erysipelas so that one may be able to better prevent and control the swine erysipelas outbreaks in Northeast China. Using spatial clusters, the study area was divided into two parts: South Central Mainland China (hot spots) and Northeast Mainland China (potential outbreak areas). We investigated a total of 31 environmental factors and used the lasso regression and k-fold cross-validation methods to determine the main factors involved. Seven risk factors were determined to have a major impact on swine erysipelas. Multiple logistic regression was used to examine the contribution of these seven risk factors to the outbreak from 2008 to 2018, in the two research regions. In South Central Mainland China, where swine erysipelas was most prevalent, the extreme maximum temperature [OR = 1.143 (95%CI: 1.032-1.342)], total precipitation [OR = 2.298 (95%CI: 1.410-5.112)] and precipitation ≥0.1 mm [OR = 2.396 (95%CI: 1.329-5.941)] exhibited positive effects. The maximum wind speed [OR = 0.550 (95%CI: 0.303-0.775)] and concentration of O3-8H-90 per [OR = 0.876 (95%CI: 0.747-0.980)] exhibited negative effects. Summer was the main season for the erysipelas epidemic in South Central Mainland China. In Northeast China, only the total precipitation [OR = 1.048 (95%CI: 0.900-0.989)] was positively correlated with the prevalence of swine erysipelas, whereas the other factors were not significant. There was no obvious seasonal feature for the epidemic. Through the comparison and analysis of risk factors between the two research regions, more attention should be given to the impacts of high temperature and precipitation on the swine erysipelas epidemic in Northeast China.

Wild boars: A potential source of Erysipelothrix rhusiopathiae infection in Japan.

The potential role of wild boars as a source of erysipelas infection was investigated. An ELISA test of wild boar serum samples from 41 prefectures in Japan revealed that proportions of the Erysipelothrix rhusiopathiae-positive samples were very high in all the prefectures, and the mean positive rate was 95.6% (1312/1372). Serovars of E. rhusiopathiae isolates from wild boars were similar to those of previously reported swine isolates, and all serovar isolates tested were found to be pathogenic to mice. These results suggest that wild boars in Japan constitute a reservoir of E. rhusiopathiae and may pose risks to other animals.

Production diseases in smallholder pig systems in rural Lao PDR.

Pigs in Lao People's Democratic Republic are important for income and food security, particularly in rural households. The majority of pigs are reared in smallholder systems, which may challenge the implementation of any disease control strategies. To investigate risk factors for pig production diseases in such farming systems in the country a serological survey was conducted during 2011. A total of 647 pigs were sampled, accounting for 294 households in Luang Prabang and 353 in Savannakhet province representing upland and lowland, respectively. The results demonstrated that pigs in Lao PDR had antibodies against erysipelas (45.2%), CSF (11.2%), PRRS (8.6%), FMD O (17.2%) and FMD Asia 1, (3.5%). Differences in the housing systems influenced disease risk, for example, penned pigs had reduced odds of FMD and CSF, compared to those in scavenger systems. Pigs owned by farms using a sanaam (a communal area where pigs are kept for some time of the year) had 3.93 (95% confidence interval (CI): 1.09-14.7) times the odds of having pigs seropositive for FMD. Farms on which sudden piglet deaths had been experienced were more likely to have pigs seropositive for FMD O and erysipelas. These diseases constrain the development of village farming and the wider livestock industry due to their impact on productivity and trade. Vaccination coverage for FMD and CSF was low and there was a lack of national funding for livestock disease control at the time of the study. Further investigation into sustainable low-cost control strategies for these pathogens is warranted.

Pathogenic characterization of Erysipelothrix rhusiopathiae Met-203 type SpaA strains from chronic and subacute swine erysipelas in Japan.

To characterize the Erysipelothrix rhusiopathiae Met-203 type surface protective antigen (Spa) A strains causing swine erysipelas in Japan, the nucleotide sequence of the hypervariable region of the spaA gene was determined in 80 E. rhusiopathiae (serotype 1a) isolates collected from pigs with chronic and subacute swine erysipelas in 14 prefectures in 2008-2014. In this study, 14 (17.5%) isolates were Met-203 type SpaA strains. We confirmed the pathogenicity of a Met-203 type SpaA strain in specific-pathogen-free pigs. In this experiment, the two challenged pigs displayed arthritis, urticaria and other clinical signs, but recovered within 10 days. Our results reveal the existence of the E. rhusiopathiae Met-203 type strains that have been causing chronic erysipelas in Japan.

Osteochondrosis, but not lameness, is more frequent among free-range pigs than confined herd-mates.

BACKGROUND: Organic pig production is expanding and amongst the objectives of organic farming are enhancing animal health and welfare. However, some studies have reported a higher prevalence of lameness and joint condemnation at slaughter in free-range/organic pigs than in conventionally raised pigs. Organic slaughter pigs have free-range housing in which indoor and outdoor access is compulsory, while in conventional farming the pigs are commonly confined to indoor pens. The present study evaluated the effects of free-range and confined housing on lameness prevalence in a herd of 106 finisher pigs, and whether osteochondrosis and Erysipelothrix rhusiopathiae associated arthritis influences these effects. We also evaluated the association between clinical lameness during the rearing period and joint condemnations at slaughter. RESULTS: Seventy free-range and 36 confined housed fattener pigs were scored for their gait twice during the rearing period and 848 joints were evaluated post mortem. Osteochondrosis was more frequent among free-range than confined pigs (P < 0.05), and when present it was also more severe (P < 0.001). Pigs with more numerous and more severe osteochondral lesions had their gait affected more than did pigs with fewer such lesions (P < 0.05). Hence it was a paradox that we did not detect more lameness among the free-range pigs than the confined pigs. E. rhusiopathiae associated arthritis was not diagnosed. The association between gait remarks/clinical lameness and joint condemnations at slaughter was not significant. CONCLUSIONS: The results indicate that free-range housing may have both positive and negative effects on locomotory traits. Free-range pigs may be less clinically affected by osteochondrosis than are confined pigs. One explanation for this effect may be strengthening of joint supportive tissue and pain relief promoted by exercise. Visual gait scoring missed serious joint lesions that probably were harmful to the pigs, and should therefore not be used as a sole indicator of joint/leg health in welfare inspection of pigs. The association between gait scores and joint condemnation appeared to be poor. This study was limited to one herd, and so more and larger studies on the effects of free-range housing on lameness severity and osteochondrosis development in pigs are recommended.

Outbreak of swine erysipelas in a semi-intensive wild boar farm in Spain.

Swine erysipelas (SE) is a disease caused by the bacterium Erysipelothrix rhusiopathiae and is one of the best-known and most serious diseases affecting domestic pigs. However, few studies exist concerning the susceptibility of wild boars to this disease and the role of this species as a reservoir. This study investigates and describes an outbreak of SE that occurred on a semi-intensive wild boar breeding farm housing 40 boars in Extremadura (SW Spain) on 11-18 February 2010. Seven animals died, of which four were examined post-mortem. Of these, three (two females and one male) were approximately 3 months old, and one was 1 year old (male). Lesions were consistent with acute septicaemia, consisting of cutaneous erythema/cyanosis and petechial haemorrhages in kidneys, urinary bladder, lungs and meninges. The 1-year-old male also had proliferative polyarthritis. Histopathology confirmed the presence of disseminated intravascular coagulation and vasculitis. Additionally, a bilateral acute panuveitis with concurrent necrotizing vasculitis and diffuse corneal oedema, neither of which have been described before in this disease, were found in the 3-month-old male boar. E. rhusiopathiae was isolated from all four animals in pure cultures from several tissues. Of these four animals, antibodies against E. rhusiopathiae, using an indirect ELISA test, were only detected in the 1-year-old male boar with polyarthritis. Posteriorly, of nine live adults tested for antibodies, four (including an adult male with polyarthritis) were positive.

Erysipelothrix spp. genotypes, serotypes, and surface protective antigen types associated with abattoir condemnations.

The objective of the current study was to investigate characteristics of Erysipelothrix spp. from slaughter condemnations. Specimens from 70 carcasses with lesions suspect for swine erysipelas were collected at an abattoir in Iowa from October 2007 to February 2009. Erysipelothrix spp. were isolated from 59 of 70 carcasses (84.3%). Abattoir inspectors classified lesions as acute, subacute, or chronic; 8 of 8 (100%) were acute cases, 31 of 32 (96.9%) were subacute cases, and 20 of 30 (66.6%) were chronic cases that were isolation positive. The following serotypes were identified: 1a (40.7%; 24/59), 2 (49.2%; 29/59), 7 (1/59), 10 (1/59), 11 (1/59), and untypeable (5.1%; 3/59). Serotypes 1a and 2 were identified in pigs with acute, subacute, or chronic clinical manifestations, whereas serotypes 7, 10, and 11 were only present in chronic cases. Fifty-seven of the 59 isolates were determined to belong to E. rhusiopathiae, and 2 of 59 of the isolates were determined to be E. tonsillarum by multiplex real-time polymerase chain reaction. Surface protective antigen (spa) A was detected in all E. rhusiopathiae isolates but not in E. tonsillarum serotypes 7 and 10. The results of the present study indicate that E. rhusiopathiae serotypes 1a and 2 continue to be commonly isolated from condemned pig carcasses and that spaA is the exclusive spa type in U.S. abattoir isolates. Interestingly, E. tonsillarum, thought to be avirulent for swine, was isolated from systemic sites from 3.4% of the carcasses that were negative for E. rhusiopathiae, indicating the potential importance of this genotype in erysipelas pathogenesis.

Characterization of Erysipelothrix species isolates from clinically affected pigs, environmental samples, and vaccine strains from six recent swine erysipelas outbreaks in the United States.

The aim of this study was to characterize Erysipelothrix sp. isolates from clinically affected pigs and their environment and compare them to the Erysipelothrix sp. vaccines used at the sites. Samples were collected during swine erysipelas outbreaks in vaccinated pigs in six Midwest United States swine operations from 2007 to 2009. Pig tissue samples were collected from 1 to 3 pigs from each site. Environmental samples (manure, feed, central-line water, oral fluids, and swabs collected from walls, feed lines, air inlets, exhaust fans, and nipple drinkers) and live vaccine samples were collected following the isolation of Erysipelothrix spp. from clinically affected pigs. All Erysipelothrix sp. isolates obtained were further characterized by serotyping. Selected isolates were further characterized by PCR assays for genotype (E. rhusiopathiae, E. tonsillarum, Erysipelothrix sp. strain 1, and Erysipelothrix sp. strain 2) and surface protective antigen (spa) type (A, B1, B2, and C). All 26 isolates obtained from affected pigs were E. rhusiopathiae, specifically, serotypes 1a, 1b, 2, and 21. From environmental samples, 56 isolates were obtained and 52/56 were E. rhusiopathiae (serotypes 1a, 1b, 2, 6, 9, 12, and 21), 3/56 were Erysipelothrix sp. strain 1 (serotypes 13 and untypeable), and one was a novel species designated Erysipelothrix sp. strain 3 (serotype untypeable). Four of six vaccines used at the sites were commercially available products and contained live E. rhusiopathiae serotype 1a. Of the remaining two vaccines, one was an autogenous live vaccine and contained live E. rhusiopathiae serotype 2 and one was a commercially produced inactivated vaccine and was described by the manufacturer to contain serotype 2 antigen. All E. rhusiopathiae isolates were positive for spaA. All Erysipelothrix sp. strain 1 isolates and the novel Erysipelothrix sp. strain 3 isolate were negative for all currently known spa types (A, B1, B2, and C). These results indicate that Erysipelothrix spp. can be isolated from the environment of clinically affected pigs; however, the identified serotypes in pigs differ from those in the environment at the selected sites. At one of the six affected sites, the vaccine strain and the isolates from clinically affected pigs were of homologous serotype; however, vaccinal and clinical isolates were of heterologous serotype at the remaining five sites, suggesting that reevaluation of vaccine efficacy using recent field strains may be warranted.

Efficacy of oral vaccination against swine erysipelas in growing-finishing pigs in a clinically infected Slovakian pig herd.

In a large Slovakian growing-finishing pig production unit, the effects of oral vaccination against swine erysipelas (SE) were investigated in three groups of pigs of 10 weeks of age. In group 1, the pigs were vaccinated intramuscularly at 1 and 3 weeks after arrival in the growing-finishing barn using an Erysipelothrix rhusiopathiae bacterin. Group 2 pigs were vaccinated at the same time as group 1 using an oral avirulent live SE vaccine administered through drinking water; the pigs in the third group were placebo treated. Clinical signs of acute SE, arthritic changes, average daily weight gain (ADG), feed conversion ratio, and mortality were evaluated. None of the pigs in groups 1 and 2 but 31.7% of the control animals (group 3) showed typical clinical signs of acute SE. More (P<0.01) non-vaccinated pigs had chronic arthritic changes compared with groups 1 and 2. No significant differences in mortality were recorded between the groups. Groups 1 and 2 had higher (P<0.05) ADG and lower feed conversion ratios compared with group 3 pigs. The results demonstrated that the oral avirulent live culture was efficacious in significantly reducing the clinical symptoms caused by E. rhusiopathiae infection, so enhancing the pigs' performance.

Concurrent swine erysipelas and Clostridium novyi infections associated with sow mortality in outdoor sows in Kenya.

A sudden increase in sow mortality was reported from a large outdoor pig-breeding unit in Kenya. The sows showed pyrexia and diamond shaped to confluent skin lesions ante-mortem. Gross pathological examination of the carcases was performed and organ samples (heart, liver, kidney, spleen, mandible lymph nodes) were sent for further diagnostic investigation. Based upon the clinical, gross- and microscopic-pathological signs, bacteriological findings and toxin testing, concurrent infection with Erysipelothrix rhusiopathiae and Clostridium novyi was diagnosed as the cause of the sow mortality.

Characterisation of Erysipelothrix rhusiopathiae isolates from pigs associated with vaccine breakdowns.

Swine erysipelas vaccines are routinely used to protect pigs against peracute and acute/urticarial forms of Erysipelothrix. Between 1995 and 1998, 34 swine herds across four Australian states experienced vaccine failure. Forty-four isolates of Erysipelothrix rhusiopathiae of serovars 2, 1a, 1b and 1bx21 were recovered from 15 of these 34 vaccine breakdown herds. These isolates were characterised by restriction fragment length polymorphism (RFLP) analyses using RsaI and AluI on whole cell DNA and for the presence of plasmid DNA. Results were compared with those of 20 isolates from 16 herds unaffected by vaccine breakdown and 13 isolates representing 10 reference strains. The majority of breakdown herds possessed isolates of serovar 2 (9/15 herds), followed by serovar 1a (5 herds). No geographic predominance of a single serovar was evident. The identification of 10 RsaI profiles from whole cell DNA among the 44 isolates from 15 breakdown herds indicated that a single, new clonal lineage of E. rhusiopathiae was not responsible for vaccine failure. RsaI RFLP analyses detected a further 14 distinct profiles among 20 field strains unassociated with vaccine breakdowns, and none matched profiles of the 10 serovar reference strains for serovars 1a, 1b, 2 or 21. This technique is recommended for epidemiological studies of E. rhusiopathiae strains.

Erysipelothrix rhusiopathiae: genetic characterization of midwest US isolates and live commercial vaccines using pulsed-field gel electrophoresis.

This is the first report of molecular characterization of US erysipelas field isolates and vaccine strains of Erysipelothrix rhusiopathiae by pulsed-field gel electrophoresis (PFGE). Erysipelas in pigs is mainly caused by E. rhusiopathiae serotypes 1a, 1b, and 2. In 2001, erysipelas reemerged as a clinical problem in pigs in the midwestern United States. In this work 90 erysipelas isolates (58 recent and 28 archived field isolates as well as 4 live-vaccine strains) were genetically characterized. Because of the limited availability of antiserum, 74/90 isolates (44/58 recent isolates) were serotyped. The serotype of the majority (79.6%) of the 44 recent isolates tested was determined to be 1a, 13.6% were serotype 1b, and 6.8% of recent isolates were serologically untypeable. Among all 90 isolates, 23 different PFGE patterns were identified. There were 43 isolates identified as serotype 1a with 4 genetic patterns: 38/43, 1A(I); 3/43, 1A(III); 1/43, 1B(V); and 1/43, 3B. Sixteen serotype 1b isolates had 11 unique genetic patterns: 4/16 were genotype 1B(III), 2/16 were genotype 3A(I), and 1/16 was in genotype groups 1A(V), 1A(VI), 1A(VII), 1B(I), 1B(IV), 1B(VII), 2, 4, and 5. Six genetic patterns were distinguished among the 10 serotype 2 isolates: 1A(IV) (1/10), 1A(V) (1/10), 1B(VI) (1/10), 2 (4/10), 7 (1/10), and 8 (2/8). Erysipelas vaccine strains (modified live) were similar to each other but different from current field strains, sharing 78.6% identity with the most prevalent genotype 1A(I) based on the PFGE-SmaI pattern. Compared with serotyping, PFGE genotyping is a more distinguishing technique, easy to perform and not dependent on the limited availability of antiserum.

An outbreak of urticarial form of swine erysipelas in a medium-scale piggery in Kiambu District, Kenya.

This report concerns an outbreak that occurred during July/August 1997. Ten pigs from a herd of 181 pigs in a medium-scale, semi-closed piggery in Kiambu District, Kenya, contracted the clinical disease. The main clinical findings in affected pigs included: fever (40.5-41.8 degrees C), prostration, inappetence, dog-sitting posture, abortion, erythema and raised, firm to the touch and easily palpated light pink to dark purple diamond-shaped to square/rectangular spots on the skin around the belly and the back. Based on the pathognomonic skin lesions, a clinical diagnosis of swine erysipelas was made. The diagnosis was confirmed by the isolation of Erysipelothrix rhusiopathiae organisms from the blood and skin biopsies taken from the affected pigs. Response to treatment with a combination of procaine penicillin and dihydrostreptomycin at the dosage rate of 20,000 IU/kg body weight (based on procaine penicillin) for 3 days was good and all the affected pigs recovered fully. The farm was placed under quarantine to prevent spread of the disease.

Acute nonfatal erysipelas in sows in a commercial farrow-to-finish operation.

Acute nonfatal erysipelas was diagnosed in 4 sows in a 1,000-sow commercial farrow-to-finish operation in Indiana. Sows were pyrexic, lethargic, lame, and had multiple, 1.3- to 7.6-cm, erythematous rhomboid skin lesions. Outbreak was attributed to failure to properly vaccinate pigs. Further morbidity and mortality were prevented by treatment of clinically affected sows and all pigs in close proximity with procaine penicillin G daily for 3 consecutive days and vaccination of all pigs with questionable vaccination status, using bacterin of killed Erysipelothrix rhusiopathiae. Periodic review of herd management protocols is important to ensure that recommended vaccination schedules are being followed and animals are receiving quality vaccinations. Human error can contribute to many production problems and should be included on the differential diagnoses list.

[Associated vaccination of pigs against swine fever, erysipelas and Aujeszky's disease]. / Asotsiirano vaksinirane na praseta sreshtu chuma, cervenka i bolestta na Aueski.

Tested was the simultaneous vaccination of pigs against swine fever, swine erysipelas, and Aujeszky's disease. Parallel to this experiment a second group of test pigs were treated with each of the three vaccines at twenty-day intervals. The effect of vaccination was assessed through clinical observations with the test groups and by challenging part of the animals with virulent strains of the swine fever and erysipelas agents. It was found that the successive application of the three vaccines at 20-day intervals (at the age of 50, 70, and 90 days) could induce immunity that lasted for a longer period than the immunity resulting from the simultaneous treatment at the age of 90 days. In order to protect the pigs for sure up to the end of the fattening period a revaccination against swine fever with the simultaneous use of the vaccine against swine erysipelas in both cases was necessary.

Isolation of Erysipelothrix rhusiopathiae from apparently healthy pigs reared under intensive and free range systems of management.

The carriage of Erysipelothrix rhusiopathiae by pigs reared under free range and intensive systems of management was compared. Large white (exotic) breeds kept under an intensive system and local (native) breeds kept under a free range system were studied. Of the 29 pigs kept under the intensive system, 44.8% carried E. rhusiopathiae in their tonsils while 51.7% of pigs kept under free range system also carried the organism in their tonsils. In each of the systems 6.9% of the pigs carried E. rhusiopathiae in their bile and muscles. Blood samples from all the animals surveyed were negative for the organism. There was no significant difference in the carriage of E. rhusiopathiae in pigs reared under the two systems of management. The ubiquity of E. rhusiopathiae in the environment, its resistance to environmental influences, poor standards of hygiene and the problem of detecting apparently healthy animals, are possible epidemiological factors which may have increased the carrier rate in the intensive system where E. rhusiopathiae was supposed to be less. The total number of carrier-pigs in the intensive system was 44.8% while in the free range system it was 51.7%.

[Quantitative methods of assessing the severity of an epizootic situation]. / Kolichestveni metodi za otsenka na napregnatostta na epizootichnata situatsiia.

n order to evaluate the epizootic status of a particular territory for a given moment or a period of time with regard to the infectious diseases one has adopted Tarshis ' formula. The present work deals with the comparative approbation of this formula, using a modified formula in which a parameter characterizing the intensity of the epizootic process was introduced. The epizootic situation and its severity was determined by the two formulas for each district of the country with regard to the following infectious diseases: gangrenous mastitis and listeriosis of sheep, swine erysipelas, and anthrax of all kinds of farm animals--all for the 1970-1981 period. A categorization of the districts is effected according to the values obtained. It was found that the modified formula is important for the objectivization of the severity of the epizootic status as it reflected also the territorial spread and intensity of the epizootic process.